Attachment for electric motors.



'w. A. LAWRENCE.

' ATTAGHMBNT FOR ELECTRIC MOTORS.

APPLICATION FILED NOV; 19, 1910.

Patented Aug. 22, 1911.

Z Inventor 4 y 2 J J J 1 25:55!

Attorneys UNITED STATES. PATENT OFEIGE,;

- WILLIAM A; LAWRENCE, or CHARLOTTE, non'rrt CAROLINA? ATTACHMENT roeELECTRIC MOTORS.

Specification off Letters Patent. Patented Aug. 22,1911.-

Application fi1ed=November 19, 1910. Serial No. 593,256.

facts will be communicated to an observe-r,

through the automatic operation of a signal.

Another object of the invention is to provide an adjustable support inwhich a contact element is held, the contact elementbeing releasablewhen an unusual degree of heat is generated in the machine, to close anelectric circuit and to operate a signal; novel means being provided foractuating the contact element, subsequent to its release.

\Vith the above and other objects in view, which will appear as thedescription proceeds, the inve tion resides in the combination andarrangement of parts and in the details of construction hereinafterdescribed and claimed, it being understood that changes in the preciseembodiment of invention herein disclosed can be made within the scope ofwhat is claimed, without departing from the spirit of the invention.

In the drawings, Figure 1 shows in side elevation, and conventionally,an electric motor to which the device of my invention has been applied;Fig. 2 shows the invention in side elevation, the View being a detailen.-

larged from Fig. 1; Fig. 3 is a section upon the line'A-B of Fig. 2,parts being shown in elevation; and Fig. 4 is a section upon the l' {eC-D of Fig.2, parts being shown in elie vation.

{in the drawings, the motor is denoted generally by the numeral 1, andthe hearing by the numeral 2, the armatmic shaft- 3 1'0- tating in thisbearing 2.

In carrying out the invention there is provided .a ring 4, adapted toi'nclose the armature shaft 2, and to be secured to the motor 1.Ordinarily, this ring 4 is secured to the motor 1 by means of screws 5.An insulatirfg sheet 6 is interposed between the ring at and the motor1, and an insulating tube 7 surrounds each of the'screws'o so asto-"insulate the said screws from the 'ring- 4. Moreover, insulatingwashers 8 are into; posed between the heads of the screws and the outerface of the ring 1. The diameter of the open ng in the ring 4 issomewhat greater than the diameter of the armature shaft 3, and byreason of this fact, a space '9 exists between the armature shaft '3 andthe inner face of the ring 4.

In the edges of the ring 4 there are a plurality of threaded radial"openings 1O.

In each opening 10 a screw is mounted,

the screw carrying a loci: nut l2 'which',en--

gaging the ring 1, serves to hold'the screw 11 against rotation. In theinner endof the screw 11 there is a channel 14, in which a contactelement 15,.ordi1iarily of copper or the like, is slidably mounted. Thiscontact element 15 is held in place-within the channel 14:, and out of'contact fwith the armature shaft 3 by means of one oran'ore- 1 touchesof solder 16', or othermaterial-which i willmelt at a very lowtemperature infact,

melt at a temperature produced by the fric-f tional heating of thearmature shaft- 3, the shaft 3 being typical of any moving part of amachine with which the device is adapted I to be assembled.

A spring 17 is seated in each of the channels 14, this spring 17 actingcompressively to force the contact element 15 outwardly, as soon as thesolder 16 has been melted away.

A binding post 18 is secured to the ring 4, and another binding post 19is secured to the motor 1. From the binding post 18 a conductor 20'leadsto an electric bell 22, which may be taken to typify any sort of signalwhich may be operated electrically. Another conductor 21 leads from thebinding post 19 to a battery 23, another conductor 24 leading from thebattery'2t to the electric bell 22.

From the foregoing explanation of the circuit, it will be seen that thering 4 upon the one hand, and the armature shaft 3 upon the other hand,form the terminals of an electrical signal circuit which is normallyopen.

In case the armature shaft 3 or its bearing should be unduly heated, thefusible mawhereupon the spring 14 will actuate the .contactelem'ents 15until one or more of i them come into bearing with the armature I shaft3. The circuit will thus be closed, and

the'bell or other signal 22 be operated, thereby lndlcating at once, anundue heating in the motor.

It is to be noted; that should the armature fshaat 3, although notoverheated, work loose material 16 is united in its hearing, so as tohave a gyrating motion, the shaft, under such circumstances,-

tact elem nt; and'the armature shaft 3 may be adj'iiste When the screws11 have thus 138611111016 [the nredetermin'ed positions, theymay-bethere held by rgotating the lock nuts 12 into abutment with thering 4:.

The ring constitutes-a holder for the screws 5-,. and the r ng 4: andthe screws 5 constitute the 'carryingmeniber for the contact elements15. Thescrews 11 act assup- .ports for the spring's'14 and the Contactelements 15. Obviously, the fusible material 16 constitutesa;-ithermostaticmeans whereby the contact-elements 15 are held in place.

By reason of the fact that this fusible with the contact element 15 andwith the screw 11, it will be noted that thescrew 11 may be rotated toadjust the position of the contact element 15 with respect tothearmature shatt 3'without in any way breaking the. continuity between thefusible material 16 and the contact ele- -1ncrit 15.

- Having thus described the invention, what is claimed is:

1. In a device or the class described, a holder adapted to be secured toa machine in the vicinity of a moving par; of the machine; a screwthreaded into the holder and provided with a channel in one end; a con-'tact element slid-able 1n the channel to'bear upon said *machine part,thereby to close an electric signal circuit of which the said part andcontact element are terminals; a spring in the channel, for slidingthe'contact element; and fusible material connecting the contact elementwith the screw to maintain the contact element spaced from said part.

2. In a device of the class described, a holder adapted to be secured toa machine in the vicinity of a moving part of the machine; a screwthreaded into the holder and provided with a channel in one end; a locknut upon the screw engaging the -holder; a contact element slidable inthe channel to bear upon said machine part, thereby to close an electricsignal circuit of which said part and the contact element. areterminals; a spring in the channel, for sliding the contact element;fusible material connecting the the contact element-spaced from saidpart.

1 In testimony that I claim the foregoing as my own, I have heretoaffixed my sigcontact element with the screw to maintain 1

